Generally, in a production process of semiconductor integrated circuit devices, a number of integrated circuits are formed on a wafer formed of silicon or the like, and probe tests are conducted in which the basic electrical characteristics of the respective integrated circuits are inspected to screen out defective integrated circuits. The wafer is then diced to obtain semiconductor chips, and each of the semiconductor chips is placed and sealed in an appropriate package. Further, burn-in tests are conducted in which electrical characteristics of the respective packaged semiconductor integrated circuit devices are inspected in a high temperature environment to screen out semiconductor integrated circuit devices having latent defects.
In an electrical inspection of the integrated circuits such as the probe test or burn-in test, a probe member is used to electrically connect the respective inspection target electrodes of the inspection target to a tester. As such a probe member, that comprising an inspection circuit board on which inspection electrodes are formed in a pattern corresponding to a pattern of the inspection target electrodes, and an anisotropic conductive elastomer sheet that is disposed on the inspection circuit board, has been known.
As anisotropic conductive elastomer sheets, those having various structures have heretofore been known. For example, Patent Document 1 discloses an anisotropic conductive elastomer sheet obtained by uniformly dispersing metal particles in an elastomer (hereinafter referred to as “dispersion-type anisotropic conductive elastomer sheet”), Patent Document 2 discloses an anisotropic conductive elastomer sheet in which a number of conductive parts extending in the thicknesswise direction of the anisotropic conductive elastomer sheet and an insulating part that insulates the conductive parts to one another are formed by non-uniformly distributing conductive magnetic particles in an elastomer (hereinafter referred to as “unevenly distributed-type anisotropic conductive elastomer sheet”), and Patent Document 3 discloses an unevenly distributed-type anisotropic conductive elastomer sheet in which surfaces of the conductive parts and the insulating part differ in level.
Since the conductive parts are formed in the unevenly distributed-type anisotropic conductive elastomer sheet in a pattern corresponding to the pattern of the inspection target electrodes of the inspection target integrated circuit, the unevenly distributed-type anisotropic conductive elastomer sheet can achieve with high reliability electrical connection of the electrodes to an integrated circuit or the like in which arrangement pitch of the inspection target electrodes, i.e., center-to-center distance between adjacent inspection target electrodes is short, as compared with the dispersion-type anisotropic conductive elastomer sheet.
Incidentally, in the probe test conducted on the integrated circuits formed on a wafer, a method is heretofore employed in which the wafer is divided into a plurality of areas in each of which 16 or 32 integrated circuits in a number of integrated circuits are formed, and the probe test is collectively conducted on all of the integrated circuits formed in one of the areas, and the probe test is then sequentially conducted on the integrated circuits formed in the remaining areas.
In recent years, it has been desired to collectively conduct the probe test on 64, 124, or all of the integrated circuits in a number of integrated circuits formed on a wafer in order to improve the inspection efficiency and reduce the inspection cost.
On the other hand, in the burn-in test, since the inspection target integrated circuit devices are minute and have poor handling capability, a long time is required to conduct electrical inspection of a number of integrated circuit devices individually, and thus the inspection cost is considerably high. By such a reason, a wafer level burn-in (WLBI) test in which a burn-in test is collectively conducted on a number of integrated circuits formed on a wafer in a state of the wafer has been proposed (see Patent Document 4).
However, when the inspection target wafer has a diameter as large as 12 inches or more and the number of inspection target electrodes is 10,000 or more, particularly 20,000 or more, for example, wherein arrangement pitch of the inspection target electrodes of each integrated circuit is extremely small, the following problems are encountered when the above anisotropic conductive connector as a probe member is used for the probe test or WLBI test.
Specifically, when inspecting a wafer having a diameter of 12 inches (about 30 cm), for example, it is necessary to use an anisotropic conductive connector that includes an anisotropic conductive elastomer sheet having a diameter of 12 inches or so.
However, when such an anisotropic conductive elastomer sheet is compressed by the wafer and the inspection circuit board, the conductive parts disposed in a peripheral area of the anisotropic conductive elastomer sheet may be sufficiently compressed, but the conductive parts disposed in a center area of the anisotropic conductive elastomer sheet are not sufficiently compressed. Therefore, conductivity of the conductive parts becomes non-uniform.
In order to sufficiently compress the conductive parts disposed in the center area of the anisotropic conductive elastomer sheet, it is necessary to press by an increased pressing force. In this case, a problem is encountered in that, since an excessive pressing force is applied to the conductive parts disposed in the peripheral area of the anisotropic conductive elastomer sheet, the conductive parts disposed in the peripheral area break and their conductivity decreases when used repeatedly, with a result that a long service life thereof could not be availed.    Patent Document 1: JP-A-51-93393    Patent Document 2: JP-A-53-147772    Patent Document 3: JP-A-61-250906    Patent Document 4: JP-A-2002-334732